1. Industrial Field
The present invention relates to a liquid crystal display for digitally driving a liquid crystal display panel and, more particularly, to a wiring between a drive section and a picture element section.
2. Prior Art
FIG. 11 is a schematic diagram showing a circuit arrangement according to a prior art. Though a plurality of source driver ICs and gate driver ICs are disposed in the liquid crystal display, a circuit signal waveform inputted to an ordinary source driver is shown in FIG. 12. Supposing that the source driver IC has an output of 300 picture element, at the time of display on a display screen, a start pulse outputted from a timing controller disposed in a control section 3 is inputted to a first source driver IC and starts to read data. When reading 1st to 300th data, the first source driver IC outputs a start pulse (shift pulse) to a second source driver IC, and the second driver IC reads the start pulse and reads 301st to 600th data. The second source driver IC outputs a start pulse (shift pulse), whereby a third source driver IC starts to operate. In this manner, a fourth source driver IC, a fifth source driver IC, sixth source driver IC . . . read data in order. After completing the data input covering 1 line to the source driver ICs, an output pulse is inputted to all of the source driver ICs, and picture element voltages corresponding to the data are outputted to picture elements of the liquid crystal panel all at once.
In the meantime, a gate driver IC also starts to operate with a start pulse, and outputs a gate signal in order of output terminals synchronously with a clock signal. When a final output terminal of the gate driver IC outputs, a start pulse (shift pulse) to a next gate driver is outputted, thus a plurality of gate drivers IC come to operate in order.
Generally, as shown in FIG. 14, the signal inputted to the source driver IC has a function of starting a data input, after the start pulse is inputted to the source driver IC, storing temporarily the data in a shift register, and outputting the picture element voltages to a picture element section 2 when an output pulse STB is inputted. Usually, the data stored temporarily in the source driver IC is picture element data covering 1 line.
In the liquid crystal display, a plurality of source driver ICs and gate driver ICs are disposed. For example, supposing that one driver has an output of 300 picture elements as shown in FIG. 15, at the time of display on a display screen, a start pulse STP outputted from the timing controller is inputted to a first source driver IC and starts to read data. When reading 1st to 300th data, a start pulse SFTP1 is outputted to a second source driver IC, and the second driver IC reads the start pulse SFTP1 and reads 301st to 600th data. At the timing of reading the final data (600th data), the second source driver IC outputs a start pulse SFTP2, whereby a third source driver IC starts to operate. In this manner, a fourth source driver IC, a fifth one, a sixth one . . . start to operate in order. After reading the data covering 1 line, the output pulse STB is inputted to each source driver IC all at once, whereby picture element voltages are outputted to the picture elements covering 1 line.
The Japanese Laid-Open Patent Publication (unexamined) Hei 4-168417 and the Japanese Laid-Open Patent Publication (unexamined) Hei 7-261711 disclosed an example according to the prior art, in which a start pulse is inputted to each source driver IC to propose a general purpose source driver IC. In this prior art, however, the output terminals of the source driver IC are made unavailable only at the rear part thereof, and therefore, for example, when the fore part of the output terminal of a TCP (tape carrier package) mounting a source driver IC thereon is not able to be wired to the picture element, this prior art is useless. Just by making unavailable both fore part and rear part of the source driver IC, the wiring from the picture elements to the substrate is more simplified. Moreover, in case of SXGA or UXGA or when number of picture elements are large thereon, number of wires for start pulse outputted from the control section by inputting a start pulse to each source driver IC is largely increased, and wiring on the substrate of the control section becomes difficult.
In the liquid crystal display, picture elements arranged forming a matrix are driven by a plurality of source driver ICs and gate driver ICs. A printed circuit board of the source driver ICs and gate driver ICs is connected to the picture element section 2 supported by a glass substrate 1 through TCP 11. 12. 13 . . . and TCP 21, 22, 23 . . . , otherwise the source driver IC and gate driver IC are directly connected to the picture element section 2 (FIG. 11).
In this case, when number of picture elements is not an integer multiplied by number of outputs in the liquid crystal display, there remains some region where any picture element is not connected to any output terminal of the source driver IC (i.e., output terminal of a TCP for source driver IC). When only the terminal end of the output of the final source driver is not connected, there is no problem even if no action is performed. However, as shown in FIG. 13, when a difference between total number of outputs of the source driver IC and number of picture elements covering one line is large, there arises a large difference in length of lead wires extending from the source driver TCP to the picture element section 2 depending upon regions, and thus there is a possibility of occurring a defective region in display due to resistance of the wires. There is a further disadvantage that distribution of wires may be difficult or sometimes the source driver TCP is oversized protruding out of width of liquid crystal panel, being restricted by a frame size.
In view of the foregoing, the present invention intends to make unavailable the output of the terminals in the fore part of the first source driver by staggering or delaying a timing when data are read by the source driver IC by, for example, changing a timing of a start pulse inputted to the source driver IC in an amount of appropriate data number. In other words, the output terminals remaining as a result of not connecting the fore part of the output terminals of the first source driver IC to the rear part of the final source driver IC, can be distributed to the fore part and the rear part.
If there is no room in the fore part and the rear part, by adjusting the timing for reading data of the driver IC in the middle part by inputting a start pulse of the driver IC in the middle part from the control section, the fore part and the rear part of the output terminals of the driver IC in the middle part are made unavailable to secure a space, and distribution in wiring from the driver IC to the picture element section is simply equalized.
A clock signal is inputted to each source driver IC, and the clock signal is largely delayed in some region due to load capacity or load resistance of the printed board and source driver ICs. Moreover, it is difficult to forecast the load capacity or load resistance of the printed board and the driver ICs, and amount of delay cannot be forecast. On the other hand, as the start pulse is directly inputted from the control section to the driver IC without passing through any other driver IC, delay of the start pulse is small. Accordingly, it is desired that the start pulse is set and fixed by securing a setup time and a hold time at a predetermined timing in the stage of trial manufacture so that the timing of the start pulse inputted to the source driver IC other than the first source driver IC may be changed by setting it from outside.
Accordingly, a liquid crystal display according to the invention comprises a plurality of drive sections for supplying a display signal to a liquid crystal display section and a control section for controlling the drive sections, in which a start pulse for indicating a start timing of the drive sections is given to a predetermined drive section at a timing different from an originally set start timing, and a part of output terminals of the drive section is made unavailable.
It is preferable that in the liquid crystal display comprising a plurality of drive sections for supplying a display signal to a liquid crystal display section and a control section for controlling the drive sections, a plurality of start pulses for indicating the start timing of the drive sections are outputted from the control section.
It is preferable that by giving the start pulses to a part or all of the drive sections at different timings, either fore part or rear part of the output terminals of the part or all of the drive sections or both fore part and rear part are made unavailable.
It is preferable that the start pulses are given to the plurality of drive sections at different timings, and the timings of giving the start pulses can be changed.
It is preferable that the control section comprises a timing controller having a function for adjusting the start pulse or start pulses and a function for controlling the drive sections.
In the liquid crystal display of above arrangement, lead wires from the driver TCP to the picture element section can be simply wired.
Furthermore, when a blanking interval of a signal for displaying an image inputted from any outside control device to the liquid crystal display is short, number of outputs of the driver IC is adjusted by making unavailable a part of the output terminals of the driver IC by idling the driver IC in the middle part of the liquid crystal display, whereby distribution in wiring can be simply performed, freedom in the arrangement of TCP is enhanced, and the TCP can be simply arranged.
Even when the clock signal inputted to the n-th driver IC distant from the first driver IC is delayed, since the function for adjusting the timing is provided, the clock signal can be set so as to be inputted at a predetermined timing by adjusting the timing even in the stage after having been designed.
Further, circuit arrangement of the control section can be simplified.
Furthermore, by equally distributing the wiring from the TCP to the picture elements, number of manufacturing steps of the wiring pattern used in the manufacturing stage of the liquid crystal panel can be reduced.
Other objects, features and advantages of the invention will become apparent in the course of the following description with reference to the accompanying drawings.